Jenson Button was told by Eric Boullier he would be returning to the McLaren racing fold
McLaren were left looking for a replacement for Fernando Alonso after agreeing to let the Spaniard miss the Monte Carlo event to race in the prestigious Indy 500 in the US.
But racing director Eric Boullier has revealed that tempting Button back out of retirement for a one-off shot at the Monaco Grand Prix was not difficult.
"I rang him and we discussed it and his first reaction was just 'great, I'm so excited'," Boullier said.
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"It was an easy discussion, to be honest – very straightforward. He was the choice.
“He had a contract with us anyway, but you could feel his excitement over the phone was real and I'm happy that it will be part of his adventure."
McLaren have struggled so far in 2017 thanks to a lack of power and reliability in their Honda power unit.
Alonso and rookie team-mate Stoffel Vandoorne have just one race completion between them and are by their own admission last in terms of speed.
Button himself is more than aware that he is unlikely to repeat his 2009 feat of victory at Monte Carlo and that a points finish would be a huge result for the team.
But the Brit will first have to meet the physical challenge of the new cars which have increased levels of downforce.
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Jenson Button and Fernando Alonso were team-mates at McLaren last season
Jenson Button last raced for McLaren in the 2016 car which is very different from the new beasts
However, Button will not drive in McLaren’s mid-season test next week because the team are confident in his experience.
"We discussed this at length together," Boullier added.
"Jenson obviously spent 17 years racing in Formula 1 and he actually drove the kind of levels of downforce we have today.
"Going through the difference on the technicalities to drive this car, we agreed that the track layout here [in Bahrain] or even practice running in Barcelona [at the Spanish GP] would not be very useful.
"He's fit, he's ready and having Oliver Turvey in the car next week is part of fine tuning the correlation with our simulator.
“Our simulator in MTC [McLaren Technology Centre] is very accurate now and we both believe that it's better for him to spend a couple of days in the simulator driving this car into the streets of Monaco."
Button said on his return: “I’m thrilled to be making a one-off return to Formula One, and I couldn’t think of a better place to make that return than my adopted home grand prix of Monaco.
“I am supremely fit, having done a lot of triathlon training recently, so I have no worries on that score. And it’ll be nice to say ‘hi’ to all my old Formula One mates, too, and hopefully to give the fans something to cheer about.”